1. Field of the Invention
The present invention relates to a thin film magnetic head employed in a magnetic recording reproduction apparatus such as a magnetic disk drive.
2. Discussion of Background
A thin film magnetic head that is mainly employed in a magnetic disk device constituting a computer storage apparatus must be able to support a high recording density. One effective means for supporting a high recording density is to increase track density. As a means for achieving this, Japanese Unexamined Patent Publication (KOKAI) No. 296907/1991, for instance, discloses a technology through which the recording track width or the reproduction track width of a thin film magnetic head is set at an extremely small value with a high degree of precision by cutting the width of the pole tip in the direction of the tracks by using a focussed ion beam.
However, the grooves disclosed in the publication cited above are provided with side wall surfaces that extend almost vertically. One of the problems with grooves structured in this manner is that during magnetic recording/reproduction operation, dust collects within the grooves, causing the electromagnetic conversion characteristics of the thin film magnetic head to become unstable or, in the worst case, causing a head crash. The dust collected in the grooves includes particles of the protective film adhered to the magnetic recording medium and the substances constituting the surface of the thin film magnetic head facing opposite the medium that are released during the magnetic recording/reproduction operation as well as dust particles from the air.
As measures for solving such dust-related problems, Japanese Unexamined Patent Publication (KOKAI) No. 296907/1991 discloses a means through which dust is prevented from collecting within the grooves by having the grooves filled with an appropriate material, and a means through which an open structure is adopted for the grooves in which no dust can collect. However, in the former means, the filler material itself may become a cause for dust formation. In addition, since the grooves must be filled with the appropriate material, the number of manufacturing steps increases.
In the case of the latter means, the length of time required for machining the grooves will increase, reducing productivity. In other words, since machining with a high degree of precision is required, focussed ion beams will normally be employed. While machining, employing a focussed ion beam, the cutting rate is low. A great deal of time is required when performing machining to form grooves by cutting the slider surface, which has a high degree of resistance against wear and abrasion, with a focussed ion beam. In the case of grooves with an open structure, the machining quantity increases and, as a result, the length of machining time required for forming the grooves also increases, thus lowering productivity.